The invention relates to a fuel injection system for a piston engine.
So-called common rail systems have frequently been applied in fuel injection systems for piston engines. In a conventional common rail system, fuel is injected into a common pressure accumulator under high pressure, wherefrom the fuel is dosed into each cylinder of the engine by controlling the action of the injector nozzle.
The common pressure accumulator must be designed to be very strong so as to withstand the high pressures which are typically of the order of >100 MPa. Similar to pressure vessels, the pressure accumulators are typically cylindrical in design. This kind of design leads to great wall thickness and thereby also, for example, the space requirement is large compared to the volume of the pressure accumulator.
Common prior art is represented by a common rail solution disclosed in the applicant's previous U.S. Pat. No. 6,240,901. In this solution, fuel is fed from the fuel tank to the pressure accumulator by means of a high pressure pump, subsequent to which the fuel is injected into cylinders of the engine by means of injectors. The fuel pressure accumulator comprises at least two separate pressure accumulator units, each of which is connected to at least two injectors and provided with an individual high pressure pump. In order to equalize pressure, the pressure chambers of the pressure accumulator units are continuously connected to each other and one of the pressure accumulator units of the system is provided with a valve, by means of which the pressure chamber of this pressure accumulator unit and the pressure chambers connected thereto can be connected to the fuel tank. This kind of solution, however, requires a relatively large space around the engine. In this publication, the pressure accumulators are described as cylindrical chambers with thick walls, which, as described in the above, leads to great wall thicknesses and, consequently, the space requirements are also relatively great.
The present invention may be used to provide a fuel injection system for a piston engine minimizing the problems associated with prior art. The present invention may specifically be used to provide a fuel injection system for a piston engine minimizing the space requirements adjacent the engine.